1. Field
The invention relates to a polyaxial bone anchoring device that includes a bone anchoring element with a head and a shank, and a receiving part for coupling the bone anchoring element to a rod. In the receiving part, a pressure element is provided that comprises flexible sections each having an inclined surface portion that cooperates with a corresponding inclined surface portion provided at the receiving part in a configuration in which the flexible sections are flexed to hold the head in an angular position with low friction before the head is locked.
2. Description of Related Art
US 2010/0234902 A1 describes a receiving part for receiving a rod for coupling the rod to a bone anchoring element. The receiving part includes an accommodation space for accommodating a head of a bone anchoring element and a pressure element arranged at least partially in the accommodation space. In one embodiment, the pressure element has two upstanding resilient fingers and the receiving part comprises two pins to secure the pressure element in the receiving part. The pins form an abutment for the fingers of the pressure element when the pressure element is in a position beneath the pins and the resilient fingers assume their unflexed condition. In this configuration the pressure element exerts a pre-stress or pre-load onto the head that provides a friction fit of the head in the receiving part.